Universal power supply system

ABSTRACT

A universal power supply system is used for at least one electric consumer. The supply system comprises at least one AC source and a cable connection connecting said AC source to said electric consumer. The AC source has associated therewith an AC/DC converter for converting the AC voltage into DC voltage. The DC voltage generated in this way is adapted to be transmitted to the electric consumer via the cable connection. To improve such a universal power supply in such a way that it is possible to provide a high and stable voltage without any additional components (such as additional heat dissipation components), the AC/DC converter comprises a plurality of AC/DC converter components which, on the input side thereof, are connected in parallel with the AC source and which, on the output side thereof are connected serially to the electric consumer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 10/489,573filed Aug. 5, 2004, which is a U.S. National Phase Application ofPCT/EP2002/010471 filed Sep. 18, 2002, which claims the benefit ofGerman Patent Application No. 20115471.4 filed Sep. 19, 2001, all ofwhich are incorporated herein by reference in their entireties for allpurposes.

DESCRIPTION

The present invention relates to a universal power supply system for atleast one electric consumer. The power supply system comprises at leastone AC source and a cable connection connecting said AC source to saidelectric consumer. The AC source has associated therewith an AC/DCconverter for converting the AC voltage into a DC voltage. The DCvoltage generated in this way is adapted to be transmitted to theelectric consumer via the cable connection.

In the case of electric consumers necessitating a high voltage and ahigh power, it turned out that the use of such a universal power supplysystem entails difficulties with respect to the generation and thestabilization of the voltage. In addition, if the AC/DC converter failsto operate, a supply of the electric consumer is no longer possible,since a redundancy with respect to the converter is normally dispensedwith for reasons of costs.

Furthermore, when AC voltage is converted into DC voltage by means ofsuch an AC/DC converter, the generation of a substantial amount of heatwithin comparatively close limits will have to be reckoned with due tolosses of the converter. This heat must be dissipated so as to preventdamage being caused to the converter or to other components of the powersupply system which are located adjacent said converter. The heat can bedissipated e.g. by active cooling systems, but this will entailadditional structural components and costs.

It is therefore the object of the present invention to improve auniversal power supply system of the type mentioned at the start in sucha way that it is possible to provide a high and stable voltage, even inthe case of high power requirements, in a reliable manner and at areasonable price, without any additional components for e.g. heatdissipation being necessary.

In connection with the features of the generic clause of claim 1, thisobject is achieved in that the AC/DC converter comprises a plurality ofAC/DC converter components which, on the input side thereof, areconnected in parallel with the AC source and which, on the output sidethereof, are connected serially to the electric consumer.

Due to this mode of connection of the AC/DC converter components, eachof these components only serves to generate a certain percentage of thevoltage on the consumer or output side of the AC/DC converter. If the DCvoltage which is to be produced on the output side amounts e.g. to 6000V, said DC voltage can be produced by e.g. 20 converter componentshaving each an output voltage of 300 V. It is also possible to provide30, 40 or 50 converter components, each of these converter componentsproviding then a respective percentage of the DC voltage required on theoutput side.

In the simplest case, the converter components all have the same type ofstructural design so that, in the case of n converter components, eachconverter component produces the n^(th) percentage of the necessaryoutput voltage from the AC voltage applied to the input side.

In contrast to an AC/DC converter for producing e.g. 6000 V, suchconverter components are easy to handle and easy to maintain. Thedissipation heat per converter component is here normally so low thatseparate cooling means can be dispensed with. If the convertercomponents are arranged comparatively close to one another, simplecooling means conducting e.g. cooling air over the converter componentswill suffice even in the case of high power. In comparison with knownconverters, the costs for cooling this AC/DC converter are, however,reduced substantially.

If one of the converter components fails to operate, the output voltagewill only be reduced by said n^(th) part so that also the remaining n−1converter components will still provide a sufficiently high voltage forthe electric consumer. Only if a plurality of converter components failsto operate, it may prove to be necessary to replace said convertercomponents, at least partially. In any case, if one or a plurality ofconverter components fails to operate, it is still guaranteed that thevoltage supplied to the electric consumer will still be sufficientlyhigh to permit operation thereof (redundancy).

A simple and reliable AC source can be seen in an embodiment in whichsaid AC source is a 380 V three-phase power source.

A converter component of the type mentioned at the beginning can bedefined e.g. by a linearly controlled converter component. Suchconverter components have, however, a comparatively low efficiency whichis in most cases as low as 25 to 50%. It follows that, in the case ofhigh power values in the kilowatt range, the dissipation power willnormally at least correspond to the power delivered. This results notonly in high energy losses but also in a cooling problem, even if aplurality of converter components is provided.

The dissipation power of the converter components can easily be reducedby implementing said converter components as switched mode (mains) powersupplies. Such a switched mode power supply is provided with a switchcausing said converter component to be connected to and separated fromthe mains e.g. in accordance with the mains voltage of 50 Hz.

The losses can be reduced still further when the switched mode powersupply is clocked independently of the mains frequency of e.g. 50 Hz.Clock pulse control at higher frequencies is preferred in thisconnection.

Various realizations of such a clocked switched mode power supply areknown. The first subdivision that can be carried out is a division intoswitched mode mains power supplies clocked on the secondary side andthose clocked on the primary side. In both said fundamental versions, itis possible that a current flows constantly into a storage capacitor ofthe switched mode mains power supply or that a current is onlydischarged at certain time instances so that the converter in questionis referred to as a feed forward converter or a fly-back converter. Inorder to obtain a compact and reliable component, the switched modemains power supply according to the present invention can, for example,be implemented as a flyback converter. This flyback converter canpreferably be clocked on the primary side so as to obtain a galvanicseparation between the input and output sides, and it can be asingle-phase or a push-pull converter. Single-phase converters are, inthis context, advantageous insofar as they normally require only onepower switch as a clock switching means. This power switch can beimplemented e.g. as a power MOSFET or as a BIMOSFET. In addition, alsothyristors may be used as clocked switching means especially when highpower values in the kilowatt range are involved.

The above-mentioned switched mode mains power supplies have, especiallyin the case of higher power values, a plurality of advantages, such as alower dissipation power, a lower weight, a smaller volume, no generationof noise, less smoothing outlay and a larger input voltage range.Switched mode mains power supplies and especially also flybackconverters are used in a great variety of fields of application, such asmicrowave ovens, computers, electronic adapting equipment forfluorescent lamps, industrial and entertainment electronics, screens,cardiac defibrillators and the like. Flyback converters are alsoexcellently suitable for use in fields of application where a high poweris required on the output side.

A pulse width modulation means, in particular a pulse width modulationmeans which is adapted to be controlled or regulated, can be providedfor activating the switching means of the flyback converter or of theswitched mode mains power supply in a suitable manner. This pulse widthmodulation means is capable of producing a series of pulses which areadapted to be varied with respect to their width and/or height and/orfrequency. A frequently used pulse modulation means is a pulse widthmodulation means. This pulse width modulation means produces a pulsewidth-modulated signal whose clock cycle ratio can be controlled inaccordance with a measured actual value of the output voltage. Themeasured actual value of the output voltage can e.g. be subtracted fromthe desired value and this difference can be supplied via a controlamplifier to the pulse width modulation means. Here, the output voltageof the control amplifier can be compared with a sawtooth voltage whosefrequency determines the switching frequency or clocking of the switchedmode mains power supply. Depending on the result of this comparison, theswitching transistor is then switched on or off, whereby a desiredoutput voltage can be adjusted.

In accordance with an advantageous embodiment, the maximum outputvoltage of the switched mode mains power supply is chosen such that itdoes not exceed a limit value below the breakdown voltage of arespective component of the switched mode mains power supply, especiallyof the switching means, so that a safety distance from the breakdownvoltage is kept.

As has already been mentioned hereinbefore, the flyback converterbelongs to the converters that are clocked on the primary side, i.e. itis galvanically separated between the input and the output.

In this connection, it may of advantage when the flyback converterprovides a plurality of galvanically separated, controlled outputvoltages.

The clock frequency of the switching means can be in the kilohertz rangeand in particular in the hundred-kilohertz range so as to permit asufficiently fast clocking of the switching means and, in thisconnection, a comparatively low dissipation power of the flybackconverter. For example, flyback converters are known, which are clockedin the range of from 20 kHz to 200 kHz. Lower and higher clockfrequencies are, however, possible as well.

In order to avoid, especially in the case of high power values, thenecessity of providing separate cooling means for the convertercomponents, said converter components can be arranged in spacedrelationship with one another. The spatial distance is, however, sosmall that, normally, it corresponds only to the dimensions of oneconverter component.

A filter means can be arranged between the AC/DC converter and theelectric consumer so that, if necessary, the DC voltage generated by theAC/DC converter can be smoothed still further.

In the case of certain electric consumers, it may prove to beadvantageous when also a signal connection is provided in addition to avoltage supply. In order to avoid the necessity of providing anadditional cable connection to the electric consumer for this purpose, ameans for coupling data signals in/out can be connected to the cableconnection, said means for coupling data signals in/out being especiallylocated between the filter means and the electric consumer. This meansfor coupling data signals in/out can, on the one hand, be used forcoupling respective data signals into the data connection for e.g.controlling the electric consumer or for supplying information thereto.In the opposite direction, data received from the electric consumer canbe coupled out from the cable connection and used e.g. for monitoringthe electric consumer by means of suitable units, such as computers andthe like.

In this connection, it must betaken into account that data transmissionon the basis of the output-side DC voltage can be effected with lessinterference and with a higher velocity than in cases in which theelectric consumer is supplied with an AC voltage.

At least the AC source and/or the AC/DC converter and/or the means forcoupling data signals in/out may have associated therewith a controllerso that the various units of the power supply system according to thepresent invention can be monitored, controlled or, if necessary,regulated more effectively. This controller can e.g. also detect whetherone of the converter components implemented as a flyback converter hasfailed. If such failure is detected, the other flyback converters can beactivated such that they compensate for the failure of said one flybackconverter in that a slightly higher output voltage is e.g. delivered byeach of the other flyback converters.

The controller can also control the pulse width modulation means in thisconnection.

The controller can not only by used for monitoring purposes alone, butit is also possible to use it for establishing a communicationconnection between the respective units of the power supply system. Thiswill be of advantage especially in cases in which the various units arearranged at comparatively large distances from one another and/or atinaccessible sites. With the aid of this communication connection,physical examination or maintenance can be limited to rare cases or tocases where the unit in question has to be replaced.

The cable connection may comprise at least one coaxial cable so that,even if high power is to be transmitted and if voltage and data aretransmitted simultaneously, said cable connection can be establishedsuch that it has a small cross-section, whereby costs will be saved,especially in the case of long distances. Since the voltage transmittedthrough the coaxial cable is a DC voltage, only line losses will occur,whereas additional attenuation losses, which are caused by atransmission of AC voltages, are avoided.

In connection with the converter components and especially the flybackconverters used as such components, attention should also be paid to thefact that each of each of said converter components should be adapted tobe controlled or regulated separately with respect to its outputvoltage. The inputs of the converter components are arranged in parallelin each converter component so that the voltage supply and,consequently, current and power are fully separated. It follows that,irrespectively of the output voltage, also the total power of the systemcan be adapted according to requirements. A completely free selection ofthe power and of the output voltage is therefore possible. Due to theuse of a plurality of converter components, an extremely exact andprecise control of the output voltage as well as of the power areadditionally obtained, since each converter component controlsindependently of the other components only its own range.

If one of the converter components fails to operate, the power supply isstill guaranteed (redundancy), since the other converter components areactivated in a suitable manner so that the power failure of theconverter component that failed to operate will be compensated for onthe output side. The respective range within which each of the stilloperative converter components has to be adjusted is extremely small,since a comparatively low increase in the voltage on the output side ofthe plurality of converter components will already lead to asubstantially higher increase in the total output voltage.

In connection with each converter component and especially in connectionwith the flyback converter it is possible to dispense with additionalcomponents, i.e. to implement said converter components e.g. asintegrated circuits comprising in addition to the actual flybackconverter other elements, such as a power factor control means, anundervoltage detection means, an overvoltage monitoring means, aso-called “soft start” and the like.

It should also be pointed out that, due to the DC voltage transmitted onthe output side to the electric consumer, thin line cross-sections arepossible especially when a coaxial cable is used as a cable connection;these thin line cross-sections permit a substantial reduction of thecable connection costs. In particular when the distances to the electricconsumer are in the kilometer range and when the distances amount to 50kilometers and more, a substantial amount of costs will be saved,although the coaxial cable can simultaneously be used for transmittingdata as well.

Expensive capacitors, such as electrolytic filter capacitors, are nolonger necessary for smoothing the DC voltage on the output side. Inaddition, power factor correction can take place directly in the flybackconverter; a suitable means for effecting this correction can beincluded in the flyback converter or rather in the integrated circuitthereof. The high clock frequency of the flyback convertersimultaneously guarantees that the AC voltage on the input side issampled in full width, whereby a high efficiency is obtained.

In the following, an advantageous embodiment of the present inventionwill be explained making reference to the figures added as drawings, inwhich:

FIG. 1 shows a schematic representation of an embodiment of theuniversal power supply system, and

FIG. 2 shows a schematic circuit diagram of an embodiment of a flybackconverter docked on the primary side and used as a converter component.

FIG. 1 shows a schematic circuit diagram of an embodiment of theuniversal power supply system 1 according to the present invention. Thisuniversal power supply system comprises a 380 V three-phase AC powersource 3. The AC voltage is adapted to be transmitted to an AC/DCconverter 5 via a line 24. This AC/DC converter 5 is composed of aplurality of AC/DC converter components 6 which are connected inparallel to the line 24 via respective input terminals 23.

The AC/DC converter components 6 are defined by a switched mode powersupply 7 and, in particular, by a flyback converter 8 clocked on theprimary side and acting as a switched mode power supply 7.

On the output side, the various converter components 6 are seriallyconnected to one another via respective output terminals 22 and they areconnected to a coaxial cable 15 acting as a cable connection 4. Via saidcable connection 4, an electric consumer 2 has electric power suppliedthereto. Between the AC/DC converter 5 and the electric consumer 2, ameans for coupling data signals in/out 13 is additionally connected tothe cable connection 4. Said means for coupling data signals in/out 13is used for feeding in respective data signals or for coupling out datasignals that have been received from the electric consumer 2 or fromunits associated therewith. A filter means 12 can be arranged betweenthe AC/DC converter 5 and the electric consumer 2 so that, if necessary,the DC voltage generated by the AC/DC converter 5 can be smoothed stillfurther. The transmission of the data signals is also effected via thecable connection 4 implemented as a coaxial cable 15.

In FIG. 1, only one electric consumer 2 is shown. Normally, a pluralityof electric consumers has supplied thereto electric power and also datavia the cable connection 4 from the universal power supply system 1according to the present invention. Such electric consumers are e.g.actuators located at sites which are far away and/or not easilyaccessible. The actuators control e.g. units of fluid lines, such asvalves, shut-off devices, restrictors, pumps and the like, so that theflow of fluid into and along the fluid line is controlled and shut offin emergency cases, such as leakage, line fractures or the like, and sothat also parameters of the fluid, of the fluid flow or of therespective units are monitored and controlled. The fluid is normally fedinto the lines under high pressure from a respective fluid source andconducted along said lines e.g. from the bottom to the surface of thesea. Since such a fluid normally contains aggressive or environmentallynoxious components, a power supply and remote control which can beeffected with the aid of the universal power supply system 1 accordingto the present invention will be of great advantage.

The remote control of the respective actuators can in this connection becarried out via the communication connection established with the aid ofthe means for coupling data signals in/out 13.

All the units of the universal power supply system 1, including, ifdesired, the electric consumer 2, are adapted to be controlled and/orregulated by a controller 14. In addition, a relevant monitoring ofparameters of the various units can be carried out. In FIG. 1, thecontroller 14 is connected to the various units via connectionsrepresented by broken lines, so as to control, regulate and/or monitorsaid units.

The switched mode power supplies 7 and flyback converters 8,respectively, can be implemented as integrated circuits. Theseintegrated circuits directly comprise respective further units, such aspower factor control means 16, undervoltage detection means 17 orovervoltage monitoring means 18. In order to simplify matters, theseadditional units are shown in FIG. 1 only in the case of one flybackconverter 8; normally, they are, however, component parts of all flybackconverters.

FIG. 2 shows a simplified embodiment for a flyback converter 8 acting asa switched mode power supply 7. The flyback converter 8 comprises atransmitter 19 consisting of a primary winding connected to the inputterminal 23 and of a secondary winding connected to the output terminal22. An effective magnetic coupling exists between these two windings.The transmitter acts as a magnetic energy storage. When a switchingmeans 9 in the form of a power transistor 10 is closed, the current willincrease in the primary winding and energy will be stored in thetransmitter. When the switching means 9 is opened, the stored energy onthe side of the secondary winding will be supplied to a smoothingcapacitor 21 via a diode 20. The stored energy is fed in, in the form ofan AC voltage, via the output terminal 22.

The respective flyback converters have their output terminals 22serially connected to the cable connection 4, cf. FIG. 1.

For activating or clocking the switching means 9, i.e. the powertransistor 10, a pulse width modulation means 11 is provided in theflyback converter 8. Said pulse width modulation means 11 produces apulse width-modulated signal whose clock cycle ratio is controlled inaccordance with the measured actual value of the output voltage. Forthis purpose, the actual value measured at the output of the flybackconverter is subtracted from the respective desired value and thisdifference is supplied, via a control amplifier of the flybackconverter, to the pulse width modulation means 11. Here, the outputvoltage of the control amplifier is compared with a sawtooth voltagewhose frequency determines the clock frequency of the flyback converter.Depending on the result of this comparison, the switching means 9 isswitched on or off and the desired output voltage is adjusted in thisway.

For controlling the flyback converter, there are integrated circuits,which can be associated with or included in each of the flybackconverters 8 according to FIG. 1. These integrated circuits alsocomprise the protection circuits, e.g. undervoltage detection means,overcurrent monitoring means, soft starting means and the like, whichare required for operating the flyback converter.

The invention claimed is:
 1. A universal power supply system for atleast one electric consumer, comprising: at least one AC source; a cableconnection connecting said AC source to said electric consumer; and anAC/DC converter for converting an AC voltage from the AC source into aDC voltage, said DC voltage being adapted to be transmitted to theelectric consumer via the cable connection: wherein the AC/DC convertercomprises a plurality of AC/DC converter components which, on the inputside thereof, are connected in parallel with the AC source and which, onthe output side thereof, are connected serially to the electricconsumer; and wherein each AC/DC converter component is operable tocontrol a power factor.
 2. The universal power supply system accordingto claim 1, wherein the AC source is a 380 V three-phase power source.3. The universal power supply system according to claim 1 wherein eachAC/DC converter component is implemented as a switched mode powersupply.
 4. The universal power supply system according to claim 3wherein the switched mode power supply is clocked on a primary side ofthe switched mode power supply.
 5. The universal power supply systemaccording to claim 4 wherein the switched mode power supply isimplemented as a flyback converter.
 6. The universal power supply systemaccording to claim 5 wherein the flyback converter comprises at leastone switching transistor.
 7. The universal power supply system accordingto claim 6 wherein the at least one switching transistor is controlledby a pulse width modulator.
 8. The universal power supply systemaccording to claim 7 wherein the output voltage of the switched modepower supply can be adjusted to any value up to a limit value below abreakdown voltage of the switching transistor of the switched mode powersupply.
 9. The universal power supply system according to claim 5wherein each flyback converter is adapted to supply an output voltagethat is galvanically separated from an input voltage.
 10. The universalpower supply system according to claim 3 wherein a clock frequency ofthe switch mode power supply is greater than one kilohertz and less thanone megahertz.
 11. The universal power supply system according to claim1 wherein the AC/DC converter components are arranged in spacedrelationships with one another such that the AC/DC converter does notneed cooling components.
 12. The universal power supply system accordingto claim 1 wherein a filter is arranged between the AC/DC converter andthe electric consumer.
 13. The universal power supply system accordingto claim 12 further comprising a data coupler/decoupler located betweenthe filter and the electric consumer, wherein the data coupler/decoupleris operable to couple data signals to the cable connection and decoupledata signals from the cable connection.
 14. The universal power supplysystem according to claim 13 further comprising a controller associatedwith at least one of a group of power supply system componentsconsisting of: the AC source; the AC/DC converter; and the datacoupler/decoupler.
 15. The universal power supply system according claim14 wherein the controller is operable to establish communication betweentwo or more components selected from the group consisting of the ACsource, the AC/DC converter, the AC/DC converter components, a pulsewidth modulator associated with each AC/DC converter, and the filter.16. The universal power supply system according to claim 1 wherein thecable connection comprises at least one coaxial cable.
 17. The universalpower supply system according to claim 1 wherein each individual AC/DCconverter component is adapted to be regulated separately with respectto its output voltage.
 18. The universal power supply system accordingto claim 1 wherein each AC/DC converter component further comprises atleast one unit selected from the group consisting of an undervoltagedetector and an overvoltage monitor.
 19. The universal power supplysystem for at least one electric consumer, comprising: at least one ACsource; a cable connection connecting said AC source to said electricconsumer; and an AC/DC converter for converting an AC voltage from theAC source into a DC voltage, said DC voltage being adapted to betransmitted to the electric consumer via the cable connection; whereinthe AC/DC converter comprises a plurality of AC/DC converter componentswhich, on the input side thereof, are connected in parallel with the ACsource and which, on the output side thereof, are connected serially tothe electric consumer; wherein each AC/DC converter component isimplemented as a switched mode power supply being clocked on a primaryside of the switched mode power supply; wherein the switched mode powersupply is implemented as a flyback converter comprising at least oneswitching transistor controlled by a pulse width modulator; and whereinthe output voltage of the switched mode power supply can be adjusted toany value up to a limit value below a breakdown voltage of the switchingtransistor of the switched mode power supply.